Last week I got my Nokia Lumia 800 and even I already have read a lot of articles and reviews about it, I am impressed about the beautiful design and the build quality.
The first problem noticed was the battery life. My HTC Titan had something like two days of battery life and the battery of my Lumia 800 was empty after just one day. At the same day I also got the Windows Phone update (7.10.8107.79) and I deactivated the Exchange Push for my work mail account. Now the battery life seems to be the same or better than on my HTC Titan.
Now the Lumia 800 (3.7-inch screen) cloud be a bit bigger for me (the Lumia 900 with a 4.3-inch Screen could be perfect). I also miss the Internet Sharing feature, but there should be an update soon to activate this feature.
Overall I really like the Nokia Lumia 800 and it will be my main phone for the next months.